1. Field of the Invention
The present invention relates to a system and method of speech evaluation.
2. Description of the Prior Art
The well-known videogame SingStar®, available for the Sony® Playstation 2® and Playstation 3® (PS3®), allows one or more players to sing along to pre-recorded music tracks in a similar manner to Karaoke, and provides a competitive gaming element by generating a score responsive to the user's singing.
To do this, SingStar compares the player's voice pitch to a target pitch sequence associated with a given pre-recorded track, and generates a score responsive to the user's pitch and timing accuracy with respect to this sequence.
However, a melody or pitch-based score is neither meaningful nor readily measurable for an increasing number of music tracks that feature rapping (i.e. rhythmically reciting a lyric without necessarily applying any tune) rather than singing.
Consequently the videogame RapStar, also for the PS3, generates a score based upon detected speech sounds rather than pitch. Specifically, for a given line of rap (i.e. a line of lyrics rapped by a user) four different speech sounds are distinguished using waveform analysis, and the score for the line of rap is based upon the proportion of correct instances of those four speech sounds within a timing tolerance of their expected position. This was previously considered sufficient to indicate whether the player was saying the right words in time to the line of rap.
However, this scheme does not provide either detailed or timely performance feedback to the player, and does not do an especially good job of distinguishing accurate rapping from random speech.
The present invention seeks to mitigate these problems.